Strategies to determine the molecular basis of chemical communication by trematodes

The identification of pheromones and chemicals that may inhibit or stimulate growth and reproduction necessarily leads to the consideration of biochemical methods to isolate and characterize these molecules. Analysis ofSchistosoma mansoni surface antigens by direct radioiodination, metabolic labeling with tritiated and(14)C-tagged hexose precursors, affinity chromatography, isoelectric focusing, hydrophobic chromatography, and competitive inhibition is presented to illustrate methods of immunochemical analysis and antigen purification. Technical problems that may arise when investigating parasite molecular biology are described. Evidence of diminished fecundity of female worms in acutely infected mice supports the theory of a "crowding effect" in murine schistosomiasis and suggests the possibility that worm secretions or metabolites may function as chemical messages to inhibit oviposition. There is also evidence that the immune response of mice to an isolated surface antigen from adult worms results in the attenuation of hepatic granulomata of challenge infections. Several hypotheses are proposed to elucidate the molecular basis for chemical communication between trematodes and analytical approaches to test these hypotheses are outlined.